Correlation Engine 2.0
Clear Search sequence regions

Sizes of these terms reflect their relevance to your search.

Despite growing interest in light-driven ion pumps for use in optogenetics, current estimates of their transport rates span two orders of magnitude due to challenges in measuring slow transport processes and determining protein concentration and/or orientation in membranes in vitro. In this study, we report, to our knowledge, the first direct quantitative measurement of light-driven Cl- transport rates of the anion pump halorohodopsin from Natronomonas pharaonis (NpHR). We used light-interfaced voltage clamp measurements on NpHR-expressing oocytes to obtain a transport rate of 219 (± 98) Cl-/protein/s for a photon flux of 630 photons/protein/s. The measurement is consistent with the literature-reported quantum efficiency of ∼30% for NpHR, i.e., 0.3 isomerizations per photon absorbed. To reconcile our measurements with an earlier-reported 20 ms rate-limiting step, or 35 turnovers/protein/s, we conducted, to our knowledge, novel consecutive single-turnover flash experiments that demonstrate that under continuous illumination, NpHR bypasses this step in the photocycle. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.


Hasin Feroz, Bryan Ferlez, Cecile Lefoulon, Tingwei Ren, Carol S Baker, John P Gajewski, Daniel J Lugar, Sandeep B Gaudana, Peter J Butler, Jonas Hühn, Matthias Lamping, Wolfgang J Parak, Julian M Hibberd, Cheryl A Kerfeld, Nicholas Smirnoff, Michael R Blatt, John H Golbeck, Manish Kumar. Light-Driven Chloride Transport Kinetics of Halorhodopsin. Biophysical journal. 2018 Jul 17;115(2):353-360

Expand section icon Mesh Tags

Expand section icon Substances

PMID: 30021110

View Full Text